There’s a wealth of data supporting the use of fish oil to improve cardiovascular health, and now there’s evidence that fish oil can be used to help maintain a healthy weight.

One theory holds that fish oil improves blood vessel function and, therefore, blood flow to exercising muscles. This results in more efficient metabolism of fat during exercise, which leads to weight loss.

A study published in the American Journal of Clinical Nutrition found that combining a fish oil supplement with regular exercise can be more effective for weight loss than either of these interventions attempted alone. Pharmaceutical companies and supplement manufacturers have gotten on the bandwagon and are now offering purified fish oil in capsules that are well tolerated and have very limited interactions with medication.

The beneficial components of fish oil are the omega-3 fatty acids, and there are three types. EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the “long-chain” forms found in fish and fish oil. ALA (alpha-linolenic acid) is a “short-chain” form found in plant sources like walnuts, flaxseed and canola and soybean oils, and is probably less effective because relatively little is converted to the more active EPA and DHA forms. Consuming up to 2 grams should be safe for most people, but more than this may increase bleeding risks and should be done only under a doctor’s supervision.

Older adults remember being given a tablespoon of cod liver oil for medicinal purposes, but this is not currently recommended because of potential risks related to contaminants as well as the cumulative effects of too much vitamin A. Similarly, you should look for fish oil supplement brands that have a good track record for purifying the oil to meet safety standards. Nature’s Bounty, GNC and CVS Pharmacy are some good examples. Check out the Environmental Defense Fund’s website (www.edf.org) for safe possibilities in your area.

The most commonly cited side effects include burping or a fishy aftertaste. Taking the capsules with meals and keeping them in the refrigerator have been shown to reduce side effects significantly. Fish oil may increase the risk of bleeding, particularly in people on blood thinners, so discuss it with your doctor. And remember, the idea is not to enjoy a fish oil supplement with a bag of chips, but to incorporate it into a healthier diet. Take 2 grams a day.